Even where bookings are made offline, travellers frequently use digital tools to inform their purchases. Statista says digital travel sales will reach $818bn by 2020 while Travel Technology Europe forecasts that 58% of travel industry businesses will raise their spend on technology in 2017.

Against this backdrop, travel tech is evolving at pace, with entrepreneurs targeting ever-narower niches in each sector of the industry. Funding is following them, with the example of AirBnB, now valued more highly than hotel groups such as InterContinental Hotels and Hyatt, exciting investors in the potential of innovative start-ups. Here are just seven companies to watch.

Founded in 2015 by Kasper Middelkoop and Kristian Valk, Hotelchamp offers smart technology for hoteliers aiming to boost direct revenue and build engagement with guests in the face of the threat posed by the online travel agents (OTAs).

The company offers a suite of conversion tools powered by artificial intelligence and machine learning technologies to incentivise online customers, helping hotels to secure greater control of the relationship and to become are less dependent on third parties.

Hotelchamp has grown in two years to a team of more than 50 employees and boasts clients including The Mandeville Hotel in London, De L’Europe in Amsterdam and Hotel Palazzo Versace in Dubai. The company has raised $4.67m of funding so far and is clocking up industry awards.

TravelPerk is a free travel booking and management platform specifically designed for business travel. It delivers tools such as centralised invoicing, simplified itinerary emails and expenses integration to deliver a seamless service to users.

The company was launched in 2015 by founders Avi Meir (who sold his previous startup Hotel Ninjas to Booking.com), Javier Suarez and Ron Levin. TravelPerk has so far raised $8.5m - in May it won the Scale Startup Competition at the TNW Conference in Amsterdam.

VizEat is a social eating platform that connects travellers and local hosts who provide authentic and immersive food experiences in their homes: dinners, cooking classes, food tours and so on. The company pitches the idea as a unique way for travellers to engage with locals from all around the world and to discover new cultures around food.

Launched in Paris by Jean-Michel Petit and Camille Rumani in 2014, the platform now has more than 25,000 hosts across 130 countries. VizEat has raised $5.55m to date, closing its most recent funding round at the end of last year.

Earlier this year, Apple selected VizEat as one of its top three apps of 2016, with CEO Tim Cook enjoying a VizEat lunch in Paris!

Its website and apps are available in English, French, German, Italian, Spanish and Chinese.

Stratajet was founded in 2011 by Jonathan Nicol, a pilot-turned computer scientist and entrepreneur. Frustrated by the inefficiency of the private jet travel industy, Nicol launched Stratajet to make private jets more accessible. The model of the company works to help operators achieve maximum efficiency, whilst driving down the price of private jet travel through adapting existing empty legs to suit customers.

Stratajet has raised $16.84m of funding already, completing its most recent Series A of $8million in May last year.

Gopili began life in 2009 under the name KelBillet, marketing itself as a site for buying and selling unused train tickets. Over time, the company has morphed into a multi-modal travel search engine, presenting data on domestic and international travel (including rail, bus, car-shares and planes), and launched across Europe as Gopili in December 2014.

Last year, the busines processed more than €70m of business — impressive for a profitable company that has only raised about 2.2 million euro. Gopili’s platform boasts 100 million users and is now available in UK, Spain, Germany, Italy and Russia.

Medigo was founded in 2014 as an online search and engagement platform helping consumers book healthcare abroad, connecting patients and doctors globally. Founded by Pawel Cebula, Ieva Soblickaite and Ugur Samut, the platform offers access to more than 900 high-quality, internationally accredited hospitals and clinics, and has thousands of expert doctors in more than 30 countries. MEDIGO has raised $11.83m to date.

The platform is completely free to use and is currently available in five languages: English, German, Spanish, Italian, and French.

Founded in 2013 by Benito Gonzalez del Valle, Anna Banicevic, Sinan Masovic and Ivan Miletic, Zizoo is disrupting the boat rental industry and building a global digital booking platform and community. The platform boasts 11,000 customer-reviewed boats in over 30 countries and provides a community model, enabling reviews, communication, location based apps and services.

The platform also provides charter companies with a photo and editorial service and a powerful inventory management tool. In total, the Austrian start-up has secured $2.75m to date.

I've been a financial journalist for more than 20 years: I've written for most of the national newspapers in the UK (plus a host of magazines and web sites) on topics related to business, economics, finance, property, investment, personal finance and entrepreneurship.I've...